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PTHREAD_BARRIER_WAIT(3P) POSIX Programmer's Manual PTHREAD_BARRIER_WAIT(3P)
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
pthread_barrier_wait — synchronize at a barrier
#include <pthread.h>
int pthread_barrier_wait(pthread_barrier_t *barrier);
The pthread_barrier_wait() function shall synchronize participating
threads at the barrier referenced by barrier. The calling thread
shall block until the required number of threads have called
pthread_barrier_wait() specifying the barrier.
When the required number of threads have called
pthread_barrier_wait() specifying the barrier, the constant
PTHREAD_BARRIER_SERIAL_THREAD shall be returned to one unspecified
thread and zero shall be returned to each of the remaining threads.
At this point, the barrier shall be reset to the state it had as a
result of the most recent pthread_barrier_init() function that
referenced it.
The constant PTHREAD_BARRIER_SERIAL_THREAD is defined in <pthread.h>
and its value shall be distinct from any other value returned by
pthread_barrier_wait().
The results are undefined if this function is called with an
uninitialized barrier.
If a signal is delivered to a thread blocked on a barrier, upon
return from the signal handler the thread shall resume waiting at the
barrier if the barrier wait has not completed (that is, if the
required number of threads have not arrived at the barrier during the
execution of the signal handler); otherwise, the thread shall
continue as normal from the completed barrier wait. Until the thread
in the signal handler returns from it, it is unspecified whether
other threads may proceed past the barrier once they have all reached
it.
A thread that has blocked on a barrier shall not prevent any
unblocked thread that is eligible to use the same processing
resources from eventually making forward progress in its execution.
Eligibility for processing resources shall be determined by the
scheduling policy.
Upon successful completion, the pthread_barrier_wait() function shall
return PTHREAD_BARRIER_SERIAL_THREAD for a single (arbitrary) thread
synchronized at the barrier and zero for each of the other threads.
Otherwise, an error number shall be returned to indicate the error.
This function shall not return an error code of [EINTR].
The following sections are informative.
None.
Applications using this function may be subject to priority
inversion, as discussed in the Base Definitions volume of
POSIX.1‐2008, Section 3.287, Priority Inversion.
If an implementation detects that the value specified by the barrier
argument to pthread_barrier_wait() does not refer to an initialized
barrier object, it is recommended that the function should fail and
report an [EINVAL] error.
None.
pthread_barrier_destroy(3p)
The Base Definitions volume of POSIX.1‐2008, Section 3.287, Priority
Inversion, Section 4.11, Memory Synchronization, pthread.h(0p)
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) In the event of any discrepancy between this version and
the original IEEE and The Open Group Standard, the original IEEE and
The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 PTHREAD_BARRIER_WAIT(3P)
Pages that refer to this page: pthread.h(0p), pthread_barrier_destroy(3p)